| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
The steam explosion is one of the explosive phenomena excited by the fall of the hot melted substance into the water. Rapid phase change is governed by the direct contact heat transfer of melted substance and water. Usually the melted substance accompanies air, when it falls into the water. The air component in the steam mixture reduces the heat transfer capacity. It is important to investigate, how the phenomena change if the air is excluded from the space above the water. Whether the explosion occurs even if the water is not at the state of subcooling, is also a matter of interest. It is necessary to judge whether the phenomena are really steam explosion or not. Where they happen to emerge, near the surface, or in the center, or at the bottom, is also important characteristics. For these purposes the test water vessel should be visualized by building the sidewall with transparent material. At the same time the space in the vessel can be kept at about 20 Torr, and the inflow of the hot melted substance have to be controlled easily.
Pressure variations are detected by a Piezo sensor, and is recorded, synchronized with the pictures taken by high speed video camera. The tin and solder (Sn63%Pb37i%)were tested, and the results were compared with our data in the past. Under the condition of the saturated pressure for the water of 30℃, the steam explosion didn't occur. Under the pressure 200 Torr it is generated. The difference between the pure metal and the alloy seems to exist, but remains as a problem for the future. Based on these results, the structure of steam explosion is to be remodeled.
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